The world’s exploding energy demand–coupled with the growing risk of catastrophic rises in sea levels and climate change driven by greenhouse gases–create a singular challenge that demands urgent policy action, energy experts said at an MIT conference yesterday.

“If we don’t throw everything we have at energy efficiency right now, and start to do things we know how to do right now [in fossil-fuel alternatives], we don’t have a chance” of halting drastic planetary changes, said Nathan Lewis, a chemist at Caltech whose research interests include new solar-power materials. Lewis spoke yesterday as part of a panel on energy at the Emerging Technologies Conference.

Robert Armstrong, an MIT chemical engineer and associate director of the MIT Energy Initiative, said meeting a projected doubling of global energy demand in 50 years, while maintaining greenhouse-gas levels below twice preindustrial levels, would require adding another global energy infrastructure of today’s scale–but with zero carbon-dioxide emissions. Considering that, right now, around 86 percent of energy consumed by humans comes from fossil fuels, “certainly these are grand challenges,” he said.

As a result, the world needs to massively implement conservation and efficiency measures, install renewable power sources, build new nuclear power plants, and sequester carbon dioxide underground, where possible, said Joseph Romm, a former assistant secretary at the U.S. Department of Energy and founder of the Center for Energy & Climate Solutions. “Global warming is going to transform the lives of every single person in this room,” he said. “Within 20 years, if not 5 years, it will become the issue, the only issue. It will require a massive redirection of capital.”

Caltech’s Lewis said the question has become one of risk management. “If we don’t cure cancer, the world will stay the same. If we don’t cure AIDS, the world will stay the same. But if we don’t solve this problem in the next 20 years, from a scientific viewpoint, the world is not ever going to be the same,” he said. “How much are we willing to spend to avoid the risk of doing something that we don’t like for the next 3,000 years or more?”

The biggest policy need is for some regulation of carbon dioxide, Lewis said. Currently, there is little economic reason for companies to pursue non-carbon-emitting alternatives or to sequester the gas.

Among renewable sources, solar power holds the largest potential to supplant a meaningful amount of fossil fuel, but all alternatives must be pursued, he added. And an international effort is needed to convince countries like China that global environmental risks greatly outweigh short-term economic considerations that drive the consumption of fossil fuels.

Kelley Fletcher, the Sustainable Energy Advanced Technology Leader at GE Global Research, said unpredictable federal policy is hurting the adoption of renewable sources. “We spend a lot of time vacillating about what policies we enact. We need solid policies that send the right signals to industry and to private citizens.” For example, he noted that without a tax credit for producing wind energy, “we would not have the 5,000 1.5 megawatt turbines in this country that GE has provided.”

Getting government to act will require far greater public awareness, said MIT’s Armstrong. He cited a recent survey in which people were asked how much extra they’d be willing to pay on their electric bill to stop climate change. The average figure: $10 per month. “There is not a lot of public resolve on the energy problem,” he said. “I’m concerned about how we generate that resolve that will be necessary to generate government action.”

Armstrong said that, among other things, MIT can serve as an objective source for solid information to guide policy decisions. “I certainly think that MIT has a strong role to play as an honest broker that provides assessments on supply and demand, technology impact, and environmental concerns,” he said after the conference.

“Most people in this room will live long enough to know what is going to come–and it will be one of their biggest single regrets. And none of us is doing enough,” said former DOE official Romm. “We solve this issue now–or we leave a ruined planet.”

I’m MIT Technology Review’s senior writer, interested in a wide range of topics including climate change, energy, and information and communication technologies. Recent projects have included traveling to China to write about GMO crop… More development there, and Germany to explore how they’ll try to ramp up renewable power while closing down nuclear plants. My 2008 feature on the Obama campaign’s social-networking operation was selected for The Best Technology Writing 2009.